Method of reusing molding-sand.



No. 793,089, PATBNTED JUNE 27,1905. W. J. PATTERSON L C. R. KNAPP.

METHOD DI" REUSING MOLDING SAND.

APPLICATION FILED JULY 18. 1904,

INVENTORS.

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WITNESSES.

@MQ M No. l793,089.

UNITED STATES Patented June 27, 1905.

PATENT GEEICE.

WILLIAM J. PATTERSON AND CHARLES R. KNAPP, OF PIITSBURG, PENN- SYLV ANIA, ASSIGNORS T() HEYL ANI) PA'ITIERSON INCORPORAIED, OF

PITTSBURG, PENNSYLVANIA, CHARIEREI) UN DER 'lI-IE SYLVA NIA.

LANS OF PENN- METHOD OF REUSING lVlOLDlNG-SAND.

SPECIFICATION forming part of Letters Patent No. 793,089, dated June 27, 1905. Application filed July 18, 1904. Serial No. 217,015.

Be it known that we, IVILLIAM J. PATTER- soN and Crm1-:Las R. KNAPP, residents of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of Reusing Molding-Sand; and we do hereby declare the following to be a full, clear, and exact description thereof.

Our invention relates to a method of reusing molding-sand where a continuous process of moldingl is employed.

In all foundry plants the sand used in making the sand molds is used over and over again, the practice being that after the castings are removed from the molds on the dumping-floor to temper the sand with water until it is of the proper consistency, screen the same, and again return it to the moldingroonl. It has been found that under certain conditions this sand when used over and over again in this way becomes full of smallglobules or kernels which produce a roughness on the mold-face, so that the castings formed therein are liable to present a rough surface. Many different theories have been advanced as tothe cause of the formation of these globules or kernels, but from whatevercause they always appear in sand that has been used over and over again too frequently; and it is the object of our invention to so treat the sand that these globules or kernels will be avoided and the quality of the sand maintained so as to produce castings with smooth and even surfaces.

To this end our invention consists in dividing the sand into separate portions, using the sand of one portion continuously during a certain period by conveying it to the molds and returning it again, allowing the sand of said portion to remain in a state of rest aftersuch a period of use, using the sand from another portion in the same manner for a certain period, and so on using from each portion and linally returning to the lirst portion.

.In the accompanying drawings we have shown an arrangement of a `foundry plant i said bin is open to permit the sand to be disprovided with means for carrying out our method.

In the drawings, Figure 1 is a plan view, and Fig. 2 is a side elevation.

In the drawings the numeral 2. designates the molding-floor, upon which are located the molding-machines 3, which may be of any suitable construction. Arranged at a suitable distance above the molding-machine is a conveycr of the well-known type consisting of a reciprocating carrier with hinged flights secured thereto. Leading from the conveyer 1 to the molding-machines 3 are the spouts 5, which are controlled by gates 6. rIhe conveyer A extends over the storage-bins T 8 9 10 l1 l2, and gates 13 in said convcyer are adapted to discharge the sand from said conveyor into said bins.

Located over the conveyer s1 is the rotary screen Il, the sand being fed to said screen by a chute 15 at the Lipper end of the elevator 1G. The lower end of the elevator 1G is preferably below the 'foundry-floor, and at the lower end of said elevator is the hopper or boot 18.

Below the storage-bins 7 8 9, &c., is the conveyer 19, which is adapted to discharge into the hopper 18 of the elevator 16. The bins 7 8 9, etc., are provided with openings 2l), by means of which the sand is withdrawn from said bins onto the conveyor 19 to be carried to the hopper IS, said openings being provided with suitable gates.

Running parallel with the molding-Hoor is the flask-conveyor 2l, upon which the flasks are placed when removed from the moldingmachines. These flasks are carried around to a point about opposite the hopper 1S, where they are removed, and at this point the molds are dumped onto the d umping-floor, where the castings are separated from the sand and the sand then shoveled into the hopper 1S.

In the practice of our invention the storagebins T, 8, 9, 10, 11, and 1Q are lilled with molding-sand, and the sand is first taken from the bin T. rlhe openingl 2() at the lower end of charged onto the conveyer 19, which conveys said sand to the hopper 18, where it is elevated by the elevator 17 and discharged into the screen 14:. Just previous to passing into the screen it is customary to temper the sand by the addition of water, which may be introduced by a suitable pipe 23. The sand passes from the screen onto the conveyer 4, whence it is carried to the molding-machines 3, the gates f 13 leading to the storage bin being closed. The sand having been introduced into the molding-machines and the molds having been formed, the flasks are then transported to the flask-conveyer 21, whence they are carried around to the dumping-Hoor 22. Here the flasks are removed and the castings taken from the molds, while the sand is shoveled into the hopper 18 and carried up and into'the screen 14, after being tempered by water admitted by pipe 23. The screen 14 acts to sift the sand and prevent any bits of castings or other objects from passing with the sand into the conveyer. screen into the conveyer 4 and is carried to the bin 7. The gate 13 of the bin 7 is opened and the sand discharged into said bin on thetop of the sand already therein. The gate 13 is then closed and the gate 2O opened, whereupon a portion of sand is removed from the bottom of the bin 7 and carried by the con- Veyer 19 to the molding-machines 3 for the` next molding operation. This operation is continued for a certain period, all the moldsduring that period being made froml sand taken from the bin 7 by using that sand over and over again. Te have discovered that sand may be reused in the molds for a certain period without the formation of the globules and kernels hereinbefore referred to, and we continue to use the sand from the bin 7 during such period-say, by way of illustration, for a days run. Ve have, moreover, discovered that by allowing this used sand to remain in a state of rest for a certain period the tendency of the sand to form globules or kernels is avoided. Accordingly after the sand in the bin 7 has been used for a days run we commence the next day by using sand from the bin 8 and continue that day with such sand from the bin 8.

we use the sand from the bin 9, and so on in rotation throughout the bins 10, 11, and 12. By the time we have used the sand from bin 12 the original portion of sand in bin 7 has been allowed to rest, and during such period has been relieved of the liability of the for- The sand passes from thev On the next succeeding day mation of globules, so that on returningto loin 7 and taking thesand therefrom it will be found' that the sand may loe used continuously for a like period without the formation of globules.

Ve have illustrated six bins for separating the sand into different portions, working one loin each day, so that in the six working days of a Week each loin will be worked from once. It may not be found necessary, however, to use so many portions or bins, and in the practice of our method we` do not Wish to limit ourselves to the number of bins employed. In some cases it may be found that twentyfour hours rest will suflice to bring the sand into proper condition for reuse. By our method, therefore, the sand may be used over and over again without the employment of rolls or other grinding devices for crushing up the globules, while at Lthe same time. the sand by being allowedvto remain in a state-of` rest does not becorneworn out so readily and!- retains more of its originalconsistency.

What we claim is- 1. The method of reusing molding-sand, consisting in dividing the sand into lseparate. portions, using one portionconti-nuously during a certain period by conveying sand therefrom to the molds and returning it to said4 por-Y tion after use to be used over again,.allo;wing the sand to remain in a state of rest after such period of use,A using sand fromanother por.- tion in thesameimanner, for a certain period,y and so on, and finally returningtothe said first portion again.

2. The method of reusing molding.- sand, consisting in dividing .the-sand into separate portions, using one portion continuously during a certain periodv by conveying the from the bottom of said portion to the molds and returning the same to the top of said porf tion after use to be used over again, allowing the sand to remain. in a state of rest after suchA period of-use, using sand fromvanother por. 100

tion in the same manner for a certain period,

and so on, and -nally returning .to thesaidy first portion again.

ln testimony whereof we, the saidWILLIAM J. VPA'rrERsoN and/CHARLES R.-KNAPP, haveV IOS hereunto set our hands.

WILLIAM y J. PATTERSON 2' CHARLES R. KNAPP.

Witnesses:

ROBERT C. TOTTEN, Gr. C. RAYMOND.

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